Don't allow ports with both client_id and local_link_connection

[Mark Goddard]

If, due to a misconfiguration in ironic, a port has both a DHCP client_id option and has fields set in local_link_connection, this should be detected and rejected with an error, since it will prevent NEO from accepting the port creation request. My guess is that the local_link_connection causes it to look for a switch that does not exist (if it's an IB port).